Meta-arguments for why the causes of our beliefs are suspect are never going to be as convincing as evidence for why the beliefs themselves are wrong.

However, even if the beliefs are correct, many people will still accept them for the wrong reasons. These "meta-arguments" are powerful psychological forces, which affect all people.

I would suspect that LW has a small bunch of people who have arrived at LW:ish beliefs because of purely rational reasoning. There's a larger group that has arrived at the same beliefs ~purely because of human biases (including the factors listed in the post). And then there's a larger yet group that has arrived at them partially because of rational reasoning, and partially because of biases.